Temperature compensating appliance



H. S. SINES TEMPERATURE COMPENSTING APPLIANQE 1 l Filed Nov. '7, 1921 2 shets-sheeb 1 'Feb.27,1923. I 1,446,995

H. S. SINES TEMPERATURE CMPENSATING APPLIANCE Filed Nov. 7, 1921 z'sheets-sheet 2 Patented Feb. 27, 1923. l

UNITED STATES vrivriziar orifice,

HAROLD S. SNES, OF CHICAGO, '.lLLIlQODlIS-v,` ASSIGNOR, BY MESNE ASSIGNMENTS, TO MINERALLAC ELECTRIC CCMPANY, OF .CHCAGQ ILLINOIS, A CORTORATION 0F ILLINOIS.

TEMPERATURE' COMPENSATING APFLIANCE. I

Application am nevember 7, 192i. semi no, 512,617.

fl 'o all il; homi may concern L Be it known that I, HAROLD 71S. Sirius, a citizen ci the United States, and resident ,of Chicago7 in the county of Cook and State oit Illinois; have invented. a cert-ain new and useful improvement in Temperature Compensating Appliances, of' which the following is a. ulh clear, concise, and exact descriptioii7 reterence being' had to the accompanyingdrawings, 'forming` a part `of this a modern light or power circuit carrying a heavy current is effected by means ot' a sensitive potential measuringr device, such as a inillivoltineter, which .is connected in shunt with a. portion of a conductor carrying the current to be measured.' In most cases, that portion olf the said current carrying conductor across which the measuring instrument` is connected is in the forni of a cable or bus bar of a material, such copper, the resistance of yvliich varies coiil siderably under changes in temperature. Changes in the temperature of such a cable or bus bar may Aresult from various causes, the principalA cause ,being changes in the load carried by the circuit of which such bar or cable forms a part. tiring,` instrument must be calibrated with regard to a. delinite potential drop across that portion oit the conductor with which the instrument is connected in shun@ the information afforded by the instrument Will be incorrect, beyond an allowable percentage of erronwvhen the temperature, and thus necessarily'the resistance, of such portion of the coinflu'ctor changesnnless sonic means is lnovided in connection. with the measuringA instrun'ient for comi'iensating ttor such changes in the thermal 21nd,' resistance characteristics of the current carrying* conductor. 'o

My invention contemplates the provision Since the meas I offa device or appliance which will compensate Vfor variations in the` resistance of v the conductor carrying` the current to be measured. rllie device ot my invention is poth reliable and uniform 'with regard to its performance` and is further characterized bythe simplicity' anddurability of its i construction, by the ease with Whichit may be installed, and by the accessibility and in- `terchangeability` of its several parts.

n the accompanyfing,- drawings illustrat-y ing' my inventiom Figure l illustrates one olf the devices of my invention in operative relation to a current carrying bus bar and a vmeasuring instrument, which is electrically connected in shunt of aportion of'such bar;

Figure -2 is a Ysec-tional view on larger scale taken on line 2.-2`ot` Figure l;

Figure 34 is a plan View of the device of Figure 2,'the cover thereof oe-ing removed;

Figure et is a section which may be regarded as taken on the line fle- '41 of Figure 3, tliisview illustrating the cover in`position; f i l 'Figure 5 is a sectional vieni taken on line .5m-5 of Figure Ml;

Figure 6 is avienT similar to Figure l;

but illustrating an installation wherein a, pluralityT of competesating` appliances are employed in connection with a` single meas urine instrument Figure l illustrates an inalla-tion wht-,1re-4 in use is made of a modified form of compensatingl appliance;

Figure 8 isan axial section of oneI of the compensating appliances illustrated in elcvation in Figure i y Figure 9 is an elevational View of a modified and simpliied embodiment of my inv ention, and Y t, l

Figure 1 0 is an axial section of the device illustra-ted in elevation .in Figure 9.

Siinliar characters oi? reference refer to similar parts throughout thel several views. .Referring first to Figure l, reterencenumoral 15 indicates a copper bus bar which may be regarded as forming part of a. light oipoiver circuit. 16 indicates a yinillivoltmeter (used as an ainmeter) Which is intended to measure the .potential drop between spaced points on said bai', and 17 in- 'screws 15a-15a which are threaded into the bar 15 and constitute means for establishing electrical connection between the bar 15 and the conductors 18 and 19. The con-- ductors 1S and 19, together with conductor 20, serve electrically to 'connect the instrument 16 and the hereinafter mentioned resistance coil of the compensating device -in proper relation to bar 15. It maybe assumed that the measuring instrument 16 is ol' any approved or conventional form, and that its resistance remains substantially constant under operating conditions.4 For reasons which will hereinafter appear, the

jresista-nce of the measuring instrument should preferably constitute but a minor part of the total resistance 'of the shunt circuit in which the said measuring instrument is connected.

Let us now refer to the compensating appliance which is illustrated in detail in ures 2 to 5 inclusive. It comprises a heat conducting post 21, the lower end ot which is. adapted to be imbedded in the metal ot that" portion ot the bar or conductor 15 which is in shunt of the measuring instrument.. The post 21 is preferably threaded at its lower end for engagement with the bar `15 and is formed oi the same lrind of metal as said bar, or at an)7 rate elia metal having the same thermal characteristics as the metal of the bar. In the present case, the post may be regarded as being formedl of copper. .4 i

Sweated or otherwise Fixed upon the post is a metal nut Q2 which facilitates its application to or removal. from the bar 15. At 23 I have illustrated the lower portion of a housing which also comprises a removable cover 24. The housing portion 23 is fixed to the post :21` conveniently by being molded thereon. Both portions of the housing are formed of some good heat insulatingland dielectric material. such, for instance. as bakelite, vulcanite, porcelain or the like Cover 2e is removably held in position bv screws indicated at u Carried by the fixed housing portion Q3 and normally concealed b vcover Q4 is a pair of metal inserts 21S- 26, reach of which is` provided with terminal screws 27 and Q8. rl`he inserts 2G-26 are preferably held in position by being molded in the material of the housing portion 23, but may, oi. course, be held firmly in position in any other suitable manner, if desired. s illust'ated in Figure 1., one ot the screws 27 is connected by conductor 19 with the bus bar` the other of saidscrews 2T being connected by conductor Q0 with one of the terminals of measuring instrument 16.' Notches form-ed in the lower edge ot cover 2st (Figures 1 and 5) accommodates conductors 19 and 20.

At 29 l. have illustrated a resistance coil. lwhich is wound upon a spool consisting ot heads 230---30 of fiber, cardboardor the like, and a hollow core 31, the 'core 31 being formed oit' copper or other material having the same thermal characteristics as the metal of the bar 15 and the post 21. Core 31 is arranged to fit snuglybut removably, over the upper end of post 21. i

The ends ot the ycoil 29 are connected to the inserts 526-26 by means of screws 'Q8-2S. the coil 29 is formed oi suitable insulated wire, (copper, if the conductor 15 is formed of copper) the resistance ot' whichwill vary correspondingly to that oi conductor 15 under similar changes in ten'iperature.

From the foregoing description it is to be understood that the' measuring instrument 16 is connected in series with the compensating coil 29. It is desirabley that the coil 29 represent a comparatively largev part of the total resistance oi.t the shunt circuit which includes the measuring instrument. ln practically all cases the resistance of the compensating coilshould constitute not less than one-half the total resistancev of the shunt circuit. ln such cases, at least titty percent compensation for variations in the temperature of conductor 15 is'obtained, usually the resistance of the compensating coil should constitute considerably more than one-halt of the resistance olf the shunt circuit which includes the measuring instrument. i

By virtue o1 the `post 21 andthe core 31, the several turns or the compensating coil will at all times have, the same temperature as the metal in which the lower end ot the post is imbedded, both the post 2l and thc core 31 beinggood conductors ot heat. Since `the core 31 and all portions of the compensating coil and thelarger portion o1I the post 21 are enclosed within a housing of heat insulating material, the temperature ot' the several turns of the compensating coil is at all times maintained at the temperature of the bar 15, irrespective of the temperature of the air outside et the heat insulating housing.

.l prefer to so calibrate the instrument 16 that` when connected as illustrated in Figure 1, it `will correctl)v measure the current in the circuit of which bar 15 forms apart when such circuit is: carrying its rated tull load. in this case, the temperature of the several turns oit the comijiensatingcoil will be substantially the same as the temperature ol the har 15.

Now let us that becaiise oli assume il At this point, l wish to state that .change in thel load carried by tliecircuit of Which bar l5 forms apart, or for some other reason, the temperature of bar l5 changes. This change in temperature is accompanied by a. change in its resistance. This change in the resstance of bar 15 would be accompanied by a more or less serious error in the indica-tion afforded by instrument 16 were the compensating device of my invention not present. However, as previously explained', the temperature of the compensating coil 29 varies with the temperature of that portion of bar 15 in which post 21 is imbedded. For tliis reason, the resistance lof coil 29 varies With the resistance of bar l5 and thus compensates for the change in the resistance ot bar 15. It' `the resistance of the coil 29 represents a sutliciently large percentage ot the total resistance of the shunt circuit including the measuring instrument, the compensation which is afforded by such coil is entirely sutiicieiit to keep the indications of the instrument 1G correct Within an allouable percentage of erior under all operating conditions.

'In the arrangement of Figure 6 I utilize a plurality ot compensating,r appliances -in connection with a single measuring instru ment. The several coils 29 of these compensating appliances are connected in series f with the measuring,` instrument and with each other. The compensating appliances oi' Figure (3 are distributed along that portion of the conductor or bus `bar l5 ivliich is in sliunt with the indicating instrument, and

thus compensate i'or the average temperature ot such portion of the conductor l5. AThis arrangement is desirable When that portion oiI the conductor Which constitutes the ammeter shunt is quite long.

lu l`igure' 8 I have illustrated 'a slightly7 `nio lified ioi'm ot compensating appliance. vThis modified appliance ditl'ers from that iiieviously described onlyv iii that one ot the metal'inseits 26 is electrically connected to postA Q1 by a jumper 50. The post 2l of the K.

device shown. iii Figure 8 not onlyr serves -a-s a heat conductor and coil. and housing sup! port, but vserves also electrically to connect one side of the compensating coil to the currentcarijf'ingconductor 15,.

.lnliigi'uie 'T'I have illustrated the use, in

connection with a single ammeter, of tivo compensating3, appliances ot the type shown in Figure t. In this case, one side ot each` be connected directly to the 4conductor 15 in the manner illustrated in Figure l."

In Figures 9 and 101 have illustrated a modified and `greatly simplilied torni ot compensating appliance Which need not be described. in detail as the reference characters appended to its several parts will suivice With whichy Iam familiar. In addition, the appliance of my invention affords a` great many practical advantages which will be readily apparent to persons familia-r withk the artto which luy-invention relates. The compensating coillis readily accessible tor ii'ispec-tion, test-ing, replacement or repair.

`The compensatingcoil is amply-'protectedr and heat insulated lby the housing Within `which it is contained, but it is nevertheless .than does anyotlier generallysimilar deadapted vto vary in temperature With the -bodiments ol my invention, it is to be.` understood that many `modifications and variations in features ot the appliance are con- ;templated, and that' my invention is to be limited merely claims. f .i

Vliat I claim is:

'1. In combination 'with a conductor carrying a current tobe measured, a measuring instrument connected iii shunt ol a portion ot saidconductor, a compensating coil in series by the scope et the appended.

with said instrument, anda heatconducting post projecting from `and liaving'one end thereof imbedded in the metal of said current carryingv conductor, said resistance coil being disposed'around saidpost. ,Y

ln combination .with a conductor carrying a current to be measured,y a-,measuring instrument connected in shunt of a portion ot said conductor, a compensating coil formed otV thesame kind of metal as said conductor, said compensating coil being connected in series 'with the instrument, and

. a heat conducting;r post projecting from. andv having one endtheieof in physical contact With the metal ofsaidcurrent carrying conduct-or, said compensating coil being` disposed around said post. n 3. In comliiination `with a conductor carrying a curientto be measured, a measuring` -instrument, a heat conducting post projecting` from and having one end thereoilZ in physical contact with said conductor, and a compensating coil closely associated ith the heat conducting post. i 1

wl. ln combination with a conductor carrying a current tobe. measured, a measuring instrument, a heat conducting,- `post projecting troni and having one end thereof in physaidcompensating' coil and the major portion ot said heat conducting post.

5. in combination with a conductor carr" inga current to be measured, a measuring instrument, a' 'heat conducting post projecting from and having one end thereof threaded into said Conductor, and a conip'ensatinl-g coil 'disposed around the other end of said heat conducting post.

G. In combination with a conductor carrying `a vcurrent to be measured, a measuring instrument, aheat'conductiiig post project in g' from and having one end thereof threaded into said conductor. and a compensating coil disposed around the otherl end ot said heat conducting post, together with a heat insulating housing enclosing said compensating coil.

7 .ln combination with a conductor carrying a current to be measured, a heat conducting post projecting from and having one end. thereot in physical contact With said conductor. a compensating coil, and a hollowY core of heat conducting metal Whereou said. compensating coil is Wound, said hollow core being adapted to tit snugly around said post.

8. ln combination with condiictoi.' carrying a curr-ent to be measured, a heat conductingv post projecting from and having one end thereotl in physical contact with said conductor, a compensating coil, and a hollow core of heat conducting metal wher-con said compensating coil `is Wound, said hollenr core being adapted to' tit snugly around said post, together with a housing oi heat insulatingl material, saidheat in sulating housing being sulziriported ou tho vpost and lying around said compensating coil.

` 9.- ln coinlbin'ation with Va conductor carrying a current, to be measured, a measuring instrument. a. heat conducting post having one end thereof threaded into said conductor, a compensating zcoil, and a hollow core ufliereon said compensating coil is `Woui'id. said core being adapted to it over `conducting post lying. within the housing and haring one oit' its ends projecting. from thev housing for physical cont-act with a current carrying conductor, and ai compensating coil also disposed Within the housing and closely associated with sai-d vpost and adapted to Tar in temperaiiire therewith.

12; A toii'ipei'ature coinpensatiiiigfv appliance comp-rising heat'V conducting post y threaded at one end toiren'gagement with a current carrying conductor, a heatinsulating housing carried' by and' lyii'ig aroundthe major portion oi. saldav post, and. a. compensating coil disposed within said housing and closelyv associated with said post and adapted to vary iii temperature therewith.

13. A temperaturel compensating appli-ance ot the class described comprising a post having one end adapted to have physical contact with a' curi-ent carrying conductor, a` heat insulating. housing lying around a# portion of said'post, andr a compensating coil haring its several turns' passing around said post and adapted tio vary in temperature therewith.

14:. .i temperature compensating appliance comprising' a heat conducting post enclosed, exceptv at one end, in a housing of heat insulating material, the exposed portion oi said post being adapted :tor physical contact with a current carrying conductor,a hol.r

low core adapted to lit around that portion of the' post Which lies within said housing', i

and a coinpensatiiig'coil wound on' said core.

l5. In a temperature compensating appliance of thev class described, a heat conducting post enclosed, except at one end, in a.v

heat insulating case,'the exposed portion ot said post being. adapted for physical'icontact with a current carrying conductor, a compensating coil Witl'iii'i said.liou'sing, a hollow core iiiiereonsaid' coi-l' is Wound, said. core being adapted to lie around' said post, `and `terminals for said coil carried by said housinc t." f 1G. ln an appliance for compensating for .temperature changes oi a conductor' carrying a current to be measured, a tWo part housingl ot insulating materia-l, a' heat conducting member entering said. housing through one wall thereof and having its' exposed extremity adaptedl for physical con tact with the current carrying' conductor, and a coinpeiisating'coil disposed 'Within the housing, said compensating coil being closely associated with said VAheat conducting member and being adapted to vary in teni per ature therewith.'

17. A temperature compensating" appliance ot the class described comprising'a housing ot insulating material, a lieat conducting member by which the' housing is carried, said heat conducting member entering'the housing through one ot' the Walls thereof, said heat conducting` member liai'iin'g its exposed end adapted tor physical conta-ctwith a current carrying conductor, and a compen-` sating coil disposed Within said housing and being closely associated with said heat conducting member and adapted to vary in temperature therewith.

18. A temperature compensating appliance comprising a housing of heat insulating material, a heat conducting member' having a portion thereof lying within the housing, said heat conducting member extending through one or" the housing Walls and having its exposed end adapted for physical contact with a current carrying conductor, acompensating coil located Within the housing, and a hollow core Whereon the compensating coil is Wound, said coil being snugly and removably fitted over that part of the heat conducting member which lies Within the housing.

19. A compensating appliance comprising a housing of heat insulating material consist-ing oit a body portion and removable cover, a heat conducting post which lies Within the housing and extends through ar `Wall thereof and has its exposed end threaded for engagement with a current carrying conductor, a spool comprising a hollow heat conducting core which is removably fitted around that portion of the heat conducting post which lies Within the housing, and a compensating'coil Wound on said spool and adapted to'vary in temperature with said post` Q0. In combination with a conductor carrying a current to be measured, a measuring instrument connected in shunt of a portion of said conductor, a compensating resistance coil in series with the measuring instrument, and a housing for said compensating coil, said housing being carried by said conductor, vand comprising in its construction heatconducting metal which is in physical contact with said conductor and likewise closely associated with said compensating coil. i

2l. In` a compensating appliance of the f class described, a spool'carried compensating coil, and a housing wherein said compensating coil isremovably mounted, said housing comprising in its construction heat conducting metal which is adapted to lie in physi-` cal contact with the metall of a current carl rying conductor, the heat conducting metal ot the housing being closely associated with the several turns of said compensating coil. In witness Whereof,"l`l1ereunto subscribe my name this 15th day of October,v 1921.

i HAROLD S. EINES. lVitnesses z' i Emu V. GUs'rAFsoN, EMILE BOURGEOIS. 

